Appearance-based stereotypes affect children and adults daily and may contribute to antisocial behavior stress, and poorer health outcomes in our society. The research described in this application examines the origins and mechanisms underlying appearance-based stereotypes. The first goal of this research is to understand the mechanisms underlying the development of the ubiquitous preferences shown by infants, children, and adults for attractive faces. Why do even young infants prefer attractive to unattractive faces and when do stereotypical expectations become attached to these preferences? By what processes do infants come to associate attractiveness with positive attributes and unattractiveness with negative attributes? Given that infants as young as 12-months of age display differential treatment of attractive and unattractive people and objects (Langlois et al., 1990), children may have some primitive knowledge of these stereotypes much earlier than might be assumed. Related to goal one, goal two is to provide a parsimonious theory of attractiveness-based preferences. Until recently, most research in this field has proceeded theoretically, without a conceptual definition 0: attractiveness, and without a conceptual rationale for its importance. We propose that faces close to the average of the population are more face-like and thus more preferred. Our last goal is to better understand the nature and extensiveness of appearance-based stereotypes. How an attractiveness stereotypes related to gender and racial stereotypes? What is the "direction" of the stereotype? Are attractive children and adults at an advantage relative to medium and less attractive children and adults, or are less attractive children and adults at a disadvantage relative to their more attractive peers? The results of these studies will provide a window into a previously hidden aspect of human nature.